Flowgrind

Advanced TCP traffic generator for Linux, FreeBSD, and Mac OS X

Flowgrind - TCP traffic generator

Flowgrind is an advanced TCP traffic generator for testing and benchmarking
Linux, FreeBSD, and Mac OS X TCP/IP
stacks. In contrast to similar tools like iperf or netperf it features a distributed architecture,
where throughput and other metrics are measured between arbitrary flowgrind server processes.

What It Can Do?

Flowgrind measures besides goodput (throughput), the application layer
interarrival time (IAT) and round-trip time (RTT),
blockcount and network transactions/s. Unlike most cross-platform
testing tools, flowgrind can output some transport layer information, which are usually internal to
the TCP/IP stack. For example, on Linux and FreeBSD this includes among others the kernel's
estimation of the end-to-end RTT, the size of the TCP congestion window (CWND) and slow start threshold
(SSTHRESH).

Flowgrind has a distributed architecture. It is split into two components: the flowgrind
daemon and the flowgrind controller. Using the controller, flows between any two systems
running the flowgrind daemon can be setup (third party tests). At regular intervals during the test the
controller collects and displays the measured results from the daemons. It can run multiple flows at
once with the same or different settings and individually schedule every one. Test and control
connection can optionally be diverted to different interfaces.

Building flowgrind

Flowgrind builds cleanly on Linux, FreeBSD, and Mac OS X. Other operating
systems are currently not planned to be supported. Flowgrind expects libxmlrpc-c to be
available. Additionally, for the optional advanced traffic generation and automatic dump support
libgsl an libpcap should be installed.

Flowgrind is built using GNU autotools on all supported platforms. You can build it using the
following commands:

# cd flowgrind
# autoreconf -i
# ./configure
# make

If you download a flowgrind release, the first step (autoreconf -i) is not needed. For more
information see the INSTALL
file.

Instructions to run a test

Start flowgrindd on all machines that should be the endpoint of a flow.

Execute flowgrind on some machine (not necessarily one of the endpoints) with
the host names of the endpoints passed through the -H option.

Assume we have 4 machines, host0, host1, host2 and host3 and flowgrind has been installed on
all of them. We want to measure flows from host1 to host2 and from host1 to host3 in parallel,
controlled from host0. First, we start flowgrindd on host1 to host3. On host0 we
execute:

# flowgrind -n 2 -F 0 -H s=host1,d=host2 -F 1 -H s=host1,d=host3

In order to not influence the test connection with control traffic, flowgrind allows to setup
the RPC control connection over a different interface. A typical scenario would be to test a
WiFi connection and run the control traffic over a wired connection.

Assume two machines running flowgrindd, each having two network adapters, one
wired, one wireless. We run flowgrind on a machine that is connected by wire to the
test machines. First machine has addresses 10.0.0.1 and 192.168.0.1, the other has addresses
10.0.0.2 and 192.168.0.1. So our host argument will be this:

# flowgrind -H s=192.168.0.1/10.0.0.1,d=192.168.0.2/10.0.0.2

In words: test from 192.168.0.1 to 192.168.0.2 on the nodes identified by 10.0.0.1 and
10.0.0.2 respectively.